1. Technical Field
The present invention relates to an optical waveguide and a method of manufacturing the same, and an optical communication module and, more particularly, an optical waveguide and a method of manufacturing the same, and an optical communication module, capable of making sure of a flexibility without change of the material, achieving a weight reduction, being cheap price, improving the manufacturing efficiency by simple method.
2. Related Art
As an example of the method of manufacturing the polymer optical waveguide in the prior art, various manufacturing methods such as                (1) the method of impregnating a film with a monomer, exposing selectively a core portion to change a refractive index, and gluing films together (selective polymerization method),        (2) the method of coating a core layer and a cladding layer and then forming a cladding portion by using the reactive ion etching (RIE method),        (3) the method of exposing/developing an ultraviolet curable resin, which is obtained by adding a photosensitive material into a polymer material, by the photolithography (direct exposure method),        (4) the method utilizing the injection molding,        (5) the method of coating a core layer and a cladding layer and exposing a core portion to change a refractive index of the core portion (photo bleaching method), and others have been proposed.        
However, the selective polymerization method in (1) has a problem with the gluing of the films. The RIE method in (2) and the direct exposure method in (3) need high cost because such methods employ the photolithography. The injection molding method in (4) has a problem about a precision of the resultant core diameter. The photo bleaching method in (5) has such a problem that a difference in refractive indexes between the core layer and the cladding layer cannot be sufficiently ensured. The RIE method in (2) and the direct exposure method in (3) can be listed as the practical manufacturing method, but these methods have a problem with a production cost as described above. All manufacturing methods in (1) to (5) needs a wide area, and are not practically fit for forming the polymer optical waveguide on the flexible plastic substrate.
In addition, when the electric wiring pattern and optical interconnection pattern (core) are manufactured, complicate and many step is needed due to manufacturing by various thin film forming process, for example, patterning, exposure and development, and etching, or so like. Therefore, there are problems that fabrication yield easily gets worse and production cost soars.